# IfcOpenShell - IFC toolkit and geometry engine
# Copyright (C) 2021 Dion Moult <dion@thinkmoult.com>
#
# This file is part of IfcOpenShell.
#
# IfcOpenShell is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# IfcOpenShell is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.

import ifcopenshell.api


class Usecase:
    def __init__(self, file, cost_item=None, products=None, prop_name=""):
        """Adds a cost item quantity that is parametrically connected to a product

        A cost item may have its subtotal calculated by multiplying a unit value
        by a quantity associated with the cost item. That quantity may be either
        manually specified or parametrically connected to a quantity on a
        product. This API function lets you create that parametric connection.

        For example, you may wish to have a cost item linked to the "NetVolume"
        quantity on all IfcSlabs. Each quantity has a name which you can
        specify. If the quantity is updated in-place (which should occur for
        Native IFC applications) then the quantity for the cost item will
        automatically update as well. If the quantity is deleted and then
        re-added, then the parametric relationship is also lost.

        This API also automatically assigns a control relationship between the
        cost item and the product, so it is not necessary to use
        ifcopenshell.api.control.assign_control.

        :param cost_item: The IfcCostItem to assign parametric quantities to
        :type cost_item: ifcopenshell.entity_instance.entity_instance
        :param products: The IfcObjects to assign parametric quantities to
        :type products: list[ifcopenshell.entity_instance.entity_instance]
        :param prop_name: The name of the quantity. If this is not specified,
            then it is assumed that there is no calculated quantity, and the
            number of objects are counted instead.
        :type prop_name: str, optional
        :return: None
        :rtype: None

        Example:

        .. code:: python

            schedule = ifcopenshell.api.run("cost.add_cost_schedule", model)
            item = ifcopenshell.api.run("cost.add_cost_item", model, cost_schedule=schedule)

            # Let's imagine a unit cost of 5.0 per unit volume
            value = ifcopenshell.api.run("cost.add_cost_value", model, parent=item)
            ifcopenshell.api.run("cost.edit_cost_value", model, cost_value=value,
                attributes={"AppliedValue": 5.0})

            slab = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcSlab")
            # Usually the quantity would be automatically calculated via a
            # graphical authoring application but let's assign a manual quantity
            # for now.
            qto = ifcopenshell.api.run("pset.add_qto", model, product=slab, name="Qto_SlabBaseQuantities")
            ifcopenshell.api.run("pset.edit_qto", model, qto=qto, properties={"NetVolume": 42.0})

            # Now let's parametrically link the slab's quantity to the cost
            # item. If the slab is edited in the future and 42.0 changes, then
            # the updated value will also automatically be applied to the cost
            # item.
            ifcopenshell.api.run("cost.assign_cost_item_quantity", model,
                cost_item=item, products=[slab], prop_name="NetVolume")
        """
        self.file = file
        self.settings = {"cost_item": cost_item, "products": products or [], "prop_name": prop_name}

    def execute(self):
        if self.settings["prop_name"]:
            self.quantities = set(self.settings["cost_item"].CostQuantities or [])
        for product in self.settings["products"]:
            ifcopenshell.api.run(
                "control.assign_control",
                self.file,
                related_object=product,
                relating_control=self.settings["cost_item"],
            )
            if self.settings["prop_name"]:
                self.add_quantity_from_related_object(product)
        if self.settings["prop_name"]:
            self.settings["cost_item"].CostQuantities = list(self.quantities)
        else:
            self.update_cost_item_count()

    def add_quantity_from_related_object(self, element):
        if not element.is_a("IfcObject"):
            return
        for relationship in element.IsDefinedBy:
            if relationship.is_a("IfcRelDefinesByProperties"):
                self.add_quantity_from_qto(relationship.RelatingPropertyDefinition)

    def add_quantity_from_qto(self, qto):
        if not qto.is_a("IfcElementQuantity"):
            return
        for prop in qto.Quantities:
            if prop.is_a("IfcPhysicalSimpleQuantity") and prop.Name.lower() == self.settings["prop_name"].lower():
                self.quantities.add(prop)

    def update_cost_item_count(self):
        # This is a bold assumption
        # https://forums.buildingsmart.org/t/how-does-a-cost-item-know-that-it-is-counting-a-controlled-product/3564
        if not self.settings["cost_item"].CostQuantities:
            return ifcopenshell.api.run(
                "cost.add_cost_item_quantity",
                self.file,
                cost_item=self.settings["cost_item"],
                ifc_class="IfcQuantityCount",
            )
        if len(self.settings["cost_item"].CostQuantities) == 1:
            quantity = self.settings["cost_item"].CostQuantities[0]
            if quantity.is_a("IfcQuantityCount"):
                count = 0
                for rel in self.settings["cost_item"].Controls:
                    count += len(rel.RelatedObjects)
                quantity[3] = count